linux-kernel - Re: [PATCH v1] ARM: dts: imx: tqma7: add lm75a sensor (rev. 01xxx)

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Date:   Thu, 9 Nov 2023 10:26:27 +0100
From:   jrodrigues <jrodrigues@...met.com>
To:     Alexander Stein <alexander.stein@...tq-group.com>
Cc:     Bruno Thomsen <bruno.thomsen@...il.com>,
        Fabio Estevam <festevam@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] ARM: dts: imx: tqma7: add lm75a sensor (rev. 01xxx)

Hi Alexander,

On Thu, 09 Nov 2023 07:57:36 +0100
Alexander Stein <alexander.stein@...tq-group.com> wrote:

> Hi João,
> 
> Am Dienstag, 7. November 2023, 07:34:32 CET schrieb Alexander Stein:
> > Hi,
> > 
> > Am Freitag, 3. November 2023, 22:07:08 CET schrieb Fabio Estevam:  
> > > [Adding Bruno and Alexander]
> > > 
> > > On Thu, Nov 2, 2023 at 7:12 PM João Rodrigues
> > > <jrodrigues@...met.com>   
> wrote:
> > > > From: João Rodrigues <jrodrigues@...met.com>
> > > > 
> > > > TQMa7x (revision 01xxx) uses a LM75A temperature sensor.
> > > > The two sensors use different I2C addresses, so we can set both
> > > > sensors simultaneously.  
> > 
> > I've contacted responsible department and I am waiting for more
> > details.  
> 
> I got response that REV.01xx was just a prototype and not released
> officially.

But REV. 01xx was not an internal-only prototype. 
Furthermore, in the board manual,
https://www.tq-group.com/filedownloads/files/products/embedded/manuals/arm/carrierboard/MBa7x/MBa7x.UM.0101.pdf
section 4.1.2, the old version is still referenced.

> 
> > Best regards,
> > Alexander
> >   
> > > > Signed-off-by: João Rodrigues <jrodrigues@...met.com>
> > > > ---
> > > > 
> > > >  arch/arm/boot/dts/nxp/imx/imx7-tqma7.dtsi | 9 +++++++--
> > > >  1 file changed, 7 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/arch/arm/boot/dts/nxp/imx/imx7-tqma7.dtsi
> > > > b/arch/arm/boot/dts/nxp/imx/imx7-tqma7.dtsi index
> > > > fe42b0a4683..3fc3130f9de 100644
> > > > --- a/arch/arm/boot/dts/nxp/imx/imx7-tqma7.dtsi
> > > > +++ b/arch/arm/boot/dts/nxp/imx/imx7-tqma7.dtsi
> > > > @@ -128,11 +128,16 @@ vgen6_reg: vldo4 {
> > > > 
> > > >                 };
> > > >         
> > > >         };
> > > > 
> > > > -       /* NXP SE97BTP with temperature sensor + eeprom */
> > > > +       /* LM75A temperature sensor, TQMa7x 01xx */
> > > > +       lm75a: temperature-sensor@48 {
> > > > +               compatible = "national,lm75a";
> > > > +               reg = <0x48>;
> > > > +       };  
> 
> I don't like the idea of adding an i2c device for everybody. This
> restricts/ affects usage of i2c address 0x48 for all rev.02xx users,
> no?

Yes, it restricts the usage of I2C address 0x48 in I2C1.
While I2C1 is not exclusive to the SoM, the TQMa7x manual states
"I2C1 is used for devices on the TQMa7x".
As a counterpoint, the MBa7x carrier board also uses I2C1.

> 
> Best regards,
> Alexander
> > > > +
> > > > +       /* NXP SE97BTP with temperature sensor + eeprom, TQMa7x
> > > > 02xx */
> > > > 
> > > >         se97b: temperature-sensor-eeprom@1e {
> > > >         
> > > >                 compatible = "nxp,se97b", "jedec,jc-42.4-temp";
> > > >                 reg = <0x1e>;
> > > > 
> > > > -               status = "okay";
> > > > 
> > > >         };
> > > >         
> > > >         /* ST M24C64 */
> > > > 
> > > > --
> > > > 2.25.1  
> 
>